Behavioral and electrophysiological effects of pallidal GABAB receptor activation and blockade on haloperidol-induced akinesia in rats.
The globus pallidus plays an important role in movement regulation. Morphological studies have revealed GABA(B) receptor expression in the globus pallidus. To investigate the behavioral and electrophysiological effects of pallidal GABA(B) receptors on haloperidol-induced akinesia, microinjection and extracellular recordings were performed in the present study. Unilateral microinjection of GABA(B) receptor agonist, baclofen, into globus pallidus produced ipsilateral dystonic posturing in haloperidol-induced akinesia rats. However, microinjection of GABA(B) receptor antagonist, CGP55845, induced contralateral dystonic posturing, suggesting the tonic activity of pallidal GABAergic neurotransmission. Micro-pressure ejection of baclofen into globus pallidus decreased the spontaneous firing of pallidal neurons. Furthermore, local administration of CGP55845 alone induced a weak but consistent increase in the frequency of pallidal firing. The presence of CGP55845 prevented baclofen-induced effects completely. From the present in vivo findings it may be concluded that pallidal GABA(B) receptors may contribute to the therapy of parkinsonian akinesia by modulating the activity of globus pallidus.
Chen
Lei
L
Department of Physiology, Faculty of Medicine, Qingdao University, Qingdao, 266071, Shandong, China. chenleiqd@163.com
Wang
Hong-Tao
HT
Han
Xiao-Hua
XH
Li
Yu-Lian
YL
Cui
Qiao-Ling
QL
Xie
Jun-Xia
JX
D000818:Animals; D001418:Baclofen / Q000008:administration & dosage / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D004421:Dystonia / Q000139:chemically induced / Q000503:physiopathology*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology; D018756:GABA Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology; D006220:Haloperidol; D007274:Injections, Intraperitoneal; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010721:Phosphinic Acids / Q000008:administration & dosage / Q000494:pharmacology; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018080:Receptors, GABA-B / Q000502:physiology*
D018492:Dopamine Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D010721:Phosphinic Acids; D011412:Propanolamines; D018080:Receptors, GABA-B; C085075:CGP 55845A; D001418:Baclofen; D006220:Haloperidol